Tracking Progress: Design Review Project Status and the Importance of RFI Timelines

The Engineering Section supports the WQCD mission by ensuring drinking water and domestic wastewater infrastructure is safely designed and operated. To help stakeholders navigate the review process for drinking water and domestic wastewater projects, we are highlighting our online tracking tools and the importance of timely responses to Requests for Information (RFI).

Enhanced Project Visibility

The Engineering Section maintains a public-facing Project Status Page that tracks every design application currently in our system. This tool is designed to give you full visibility into your submittal's journey. By using this page, you can identify:

• Your Review Team: Quickly identify the assigned Review Engineer and the Quality Control (QC) Engineer for your specific project.
• Active Projects: See which projects are currently under review by our engineering staff or if we are waiting for more information from the applicant.
• Backlog/Awaiting Payment: Projects only enter the backlog once invoices are paid (if applicable). These are queued and awaiting staff availability.
• Historic Projects: This includes a record of projects that have been completed, closed, or canceled.

By checking these status updates regularly, you can better estimate your project’s timeline and ensure the "ball" isn't accidentally left in your court.

Why Timely Responses Matter

A critical part of the technical review is the Request for Information (RFI), which our engineers use to seek clarification or additional details to ensure the design meets Department Design Criteria.

To keep our review queue accurate and focused on construction-ready projects, we are implementing a new administrative update:

• Important: If a project remains in an "Awaiting More Info" status for more than 120 days without communication, the project will be flagged and may be closed out in the future.

What this means for you:

• Project Closure: If an RFI goes unanswered for over four months, the project will be flagged for potential closure. Additional communications will be sent to the applicant alerting them of the need to respond.
• The Resubmission Requirement: If a project is closed, it cannot be "reopened." To move forward, the applicant must resubmit a new design application, which includes paying new application fees (if applicable) and restarting the review at the back of the current queue.
• Stay Updated: We will always notify entities before closing a project for lack of response, but the best way to avoid delays is to respond to RFIs as soon as possible.

Keeping the Queue Moving

Responding promptly helps us all. Idle projects make it difficult to forecast workloads and assign resources to those ready for construction.

Our ask to you:

• Check your status: Regularly visit our Project Status Page.
• Respond Promptly: Aim to address RFI comments as soon as they are received.
• Stay in Touch: If you anticipate a delay in responding to an RFI, contact your assigned reviewer to keep the Department updated.

We value your partnership in protecting Colorado’s water resources. Let’s work together to keep the application process flowing smoothly.

➽ Clayton Moores, Engineering Section Manager

Design Criteria Update 2024

The Design Criteria for Potable Water Systems (Safe Drinking Water Program Policy 5) are a key policy document for the department to make decisions on approval of new designs for water sources, treatment, and storage facilities. The document also serves as a guideline for repairing or upgrading waterworks that are cited as significant deficiencies during the department’s sanitary surveys. While systems are not required to modify their waterworks to meet the design criteria unless their current waterworks are deficient, they are required to consider the criteria as acceptable fixes whenever their current waterworks are found to be deficient.

The Design Criteria were last updated in 2022. While the Department generally performs updates every 4-5 years, the department decided that a limited update was needed in 2024 because the Environmental Protection Agency (EPA) set maximum contaminant levels (MCLs) for five per and polyfluoroalkyl substances (PFAS) in April 2024. 

This update incorporated PFAS treatment criteria into Chapter 4 - Treatment, and added PFAS to the source water testing requirements in Chapter 1.2.3 Water Quality Data. The Department also used the update project as an opportunity to address internal and external feedback on Chapter 7 - Storage Tanks, and Appendix A, and align these sections more accurately with our existing business processes. Editorial changes were made throughout these sections to correct errors and inconsistencies and clarify language.

Like in previous updates, the department convened groups of stakeholders to work on the criteria. There were two external workgroups and one internal workgroup: Storage Tanks, PFAS Treatment, and Appendix A (design review submittal requirements). Generally, the overall structure of this document remained the same between 2013, 2017, 2022, and 2024 including section headings and names. The following describes the updates to each section that came out of the workgroups:

• PFAS Treatment: The PFAS treatment workgroup incorporated treatment requirements for PFAS removal to align with EPA’s PFAS MCL. This update primarily focused on 4.10 Adsorptive Media. The updates to this section include minimum empty bed contact times and maximum flow rates for granular activated carbon, non regenerating ion exchange, and engineered resin media. Additional design submittal requirements were added for media selection justification, design capacity, operations and control strategy. Language was also added outlining when piloting is and is not required for adsorptive media treatment systems. The workgroup took into consideration the impacts that the updated requirements would have on small public water systems. 
• Storage Tanks: The storage tank workgroup focused on updating Chapter 7. The workgroup added language in 7.0.10 Roof and Sidewall that no longer allows corrugated roofs on storage tanks and clarified the requirements for storage tank interior construction materials due to difficulty protecting these types of roofs from contamination. The workgroup also further clarified requirements for vents, overflows, drains, and access openings after gathering internal and external feedback since the last update. 
• Appendix A: The internal Department workgroup updated Appendix A which covers the design review submittal requirements. This workgroup aligned Appendix A with the current Department business practices. Appendix A, Table A.1 was updated and now outlines if a waterworks project needs: Department design review, monitoring plan updates, professional engineer for community water systems, and the corrosion category. The workgroup's effort resulted in changes to the Design Criteria and not just Appendix A. 
• The Introduction and Chapter 1 were updated to reflect the changes to Appendix A including the removal of the limited scope process. 
• Chapter 4, Section 4.4.2 was updated related to 4-log virus inactivation capacity for triggered groundwater systems. Section 4.4.2 was updated to align with the Regulation 11 requirement for groundwater systems to maintain 0.2 mg/L at the entry point instead of requiring the capacity for 4-log virus inactivation. The Department still strongly recommends 4-log virus inactivation for triggered groundwater systems but the Department does not have staff resources to devote to this requirement given the limited amount of Fecal Indicator-Positive monitoring events in Colorado. The Department also has a strong and long-standing approach to evaluating water sources for being under the direct influence of surface water, so we do not view this change as jeopardizing public health protection.

➽Chelsea Cotton, Lead Drinking Water Engineer

Storage Tank Roofs - Issues with Metal and Corrugated Metal Roofs

Since Colorado’s storage tank rule went into effect in 2016 we have published many articles on different aspects of finished water storage tanks. Today we would like to focus on another important potential avenue of contamination, corrugated and metal storage tank roofs. 

In recent inspections for systems that have tanks with sheet metal and corrugated metal roofs, the water quality control division (division) has seen an increase in issues with seals between the roof of the tank, and the tank walls, vents, and access hatches. Corrugated tank roofs are of particular concern due to the gaps created by their corrugated ridges. Below are some of our most important lessons learned about metal and corrugated tank roofs.

Corrugated Tank Roofs Can be Difficult to Seal

The voids created between the ridges of a corrugated roof and the walls of a tank can be difficult to effectively seal and may be a desirable shelter for rodents and other small animals. It is also much more challenging to correctly seal roof penetrations for things like tank vents in a corrugated roof. If your system has a preexisting tank with a corrugated roof the division recommends more frequent periodic inspections of these tanks with a particular focus on the seals around the corrugated materials. 

Figure 1 - Improper seal between two corrugated panels

Figure 2 & 3 - Gaps left between corrugated roof and tank walls that can allow rodents and bugs to enter the tank, creating a public health risk.

Figure 4 - Light is visible from the interior of a tank around a vent in a corrugated roof showing that it is improperly sealed.

Figure 5 - Improper seal around a tank hatch.

Expanding Foam is not an Effective Method to Seal Gaps in Tank Openings

Figure 6 - Foam used to seal the interior of a tank.

It is not uncommon to see expanding foam used to seal gaps in corrugated tanks because it can easily fill large gaps. The use of this foam can lead to potential public health risks and sanitary defects. Foam used in exterior gaps can degrade rapidly due to weather and may be used by small animals as nesting material. Foam that is used as a sealant on the interior of tanks may deteriorate and flake off into the water posing a contamination risk itself over time. Condensation collecting on the foam can leach contaminants and then drip into the drinking water.

Metal Tank Roofs Can be Challenging to Inspect

We have seen tanks with metal roofs where it isn’t possible to examine the interface between the walls of the tanks and the metal roof without an interior inspection. A dislocation or break in the gasket material or a warpage or dislocation of the metal panels could allow the entrance of contaminants such as plants, insects, birds, and small animals into the tank. A brief walk around a tank is not effective in finding potential openings. An extendable mirror can be helpful for looking at tough to see locations around all storage tanks.

Drinking Water Design Criteria for Tanks

The division has outlined the requirements for tank roofs in the design criteria. This section of the criteria is currency undergoing a stakeholder update process. If you are interested in receiving updates on this process or getting involved you can find more information on our Drinking Water Design Criteria webpage. 

New or modified storage tanks being submitted to the Department for approval must meet the design criteria. Also, the Department intends to update the design criteria to clarify that we will not approve tanks moving forward with corrugated metal roofing. However, during a sanitary survey an inspector will not issue a significant deficiency solely based on your existing tank not meeting the current design requirements unless there is a condition identified during the sanitary survey that is a potential threat to public health (examples include unprotected openings to tanks, missing/damaged screens, unsealed/un-gasketed hatches, improperly sealed tank roofs, etc.).

Figure 7 - Excerpt from the current Design Criteria for Potable Water Systems (2022 Edition)

Identification of Sanitary Defects and Risks to Public Health

If a supplier finds an animal or other concerning debris in an improperly sealed storage tank please contact the division’s emergency line at 1-877-518-5608 as soon as possible but within 24 hours of discovery. The drinking water acute team will consult with you on next steps.

If suppliers identify a sanitary defect, it must be documented upon discovery. Also, a corrective action schedule in accordance with the Storage Tank Plan must be developed to fix it as soon as possible. Take photographs before and after making repairs. By doing so, suppliers can avoid a violation for not correctly implementing the storage tank rule.

Sanitary defects that are discovered during sanitary surveys may be cited as significant deficiencies or possibly even as a Tier 2 (treatment technique) violation of the storage tank rule for permitting a known sanitary defect. The risk of violations is especially present for defects that should be ‘obvious’ to anyone performing a periodic tank inspection.

Additionally, if suppliers do not follow the corrective action schedule that they developed, they will also be in violation of the storage tank rule. Avoid violations of the storage tank rule by proactively identifying sanitary defects and then documenting that the supplier is following a corrective action schedule to fix them.

➽ Chelsea Cotton, P.E., Lead Drinking Water Engineer